Selective determination of ethyl acetate, acetone, ethanol, and methyl ethyl ketone using quartz crystal nanobalance combined with principle component analysis.

Quartz crystal nanobalance (QCN) sensors are considered as powerful mass sensitive sensors to determine materials in the subnanogram level. In the current study a method based on QCN modified with polyethylene glycol (PEG) has been developed to determine organic vapors (ethyl acetate, acetone, ethanol and methyl ethyl ketone). The frequency shift of QCN was found to be linear against analytes concentrations in the range between 4 to 35 mg/L for acetone vapor and 4-70 mg/L for 3 other vapors. The correlation coefficients for ethyl acetate, acetone, ethanol, and methyl ethyl ketone were 0.9971, 0.9976, 0.9984 and 0.9927, respectively. The principal component analysis was also utilized to process the frequency response data of the organic vapors. Using principal component analysis, it was found that over 95% of the data variance could still be explained by use of two principal components (PC1 and PC2). Subsequently, the successful discrimination of ethyl acetate and other compounds was possible through the principal component analysis of the transient responses of the PEG-modified QCN sensor.